Power supplies are widely used in electronic devices. Generally speaking, a number of different features or functions may be desirable for power supplies. These functions include, for example, power compensation, current adjustment, Line over-voltage protection, Line under-voltage protection, external on/off, etc. Not every function, however, it necessary for a given power supply as used in a particular application (e.g., electronic device). Thus, for instance, it may be desirable in one application for a power supply to have a power limit (or compensation) function, but not a Line over-voltage protection function. In another application, it may be desirable for a power supply to have a Line over-voltage protection function, but not a current adjustment function.
A designer or manufacturer of many electronic devices may be required to provide a different type of power supply for each device depending on the features or functions which are desirable for that device. From the viewpoint of the designer or manufacturer, it is more convenient to be able to use the same basic components for implementing the different power supplies which are necessary for the various electronic devices.
For example, a power supply can be implemented using a power switch and a controller. In such case, the controller may support one or more of the functions which are desired for the power supply. A power supply designer may desire to configure the power supply controller of a switched mode power supply in particular application and/or operating conditions. For instance, there may be one application in which the power supply designer would like the power supply controller to have one particular functionality and there may be another application in which the power supply designer would like the power supply controller to have another particular functionality. It would be convenient for power supply designer to be able to use the same integrated power supply controller for these different functions.